Hoooowwwwdy!

Like said above you should be able to put a 1/4 inch stud in the bottom of mirror and get a nut and lock waher , the screw is a #10 IIRC and you can get a stainless screw a Lowes eith taper seat. It only has to be like 1-1-1/2 inches long. Oh yeah welcome to site. Do you have the mirror base gasket also. Just measure the distance from front of door to mirror on drivers side then laout gasket b4 drilling your holes. Oh yeah welcome to the site.